1. Field of the Invention
The present invention relates to closures/fitments for application to a container. Specifically, the present invention relates to a closure for application to a gable top carton through use of induction heating.
2. Description of the Related Art
The traditional gable top carton has been augmented with the inclusion of a closure to access the carton's product, usually orange juice or milk. The closure is generally composed of a flange, spout and cap. The closure not only provides for enhanced resealability after accessing the product, but also creates a perception in the consumer's mind of a higher quality product.
In the majority of operations, the closure is attached to a carton on a packaging machine prior to filling. The attachment usually occurs through use of an ultrasonic horn device. One such applicator, a rotary type, is disclosed in U.S. Pat. No. 5,484,374. Another ultrasonic applicator, a linear type, is disclosed in U.S. Pat. No. 5,601,669. Ultrasonic applicators usually apply a closure to a carton by positioning an anvil, with a closure attached, into the open end of the carton. The anvil is then translationally moved towards an ultrasonic horn wherein the closure is placed through an incision in the carton. The ultrasonic horn and the anvil engage the closure and carton wall. The ultrasonic horn is then actuated to deliver a burst of ultrasonic energy to the closure and carton thereby sealing the closure to the carton. Although ultrasonic applicators adequately seal closures to a container, there are some negatives associated with the use of ultrasonic applicators on packaging machines. The greatest negative is the noise generated by the ultrasonic applicator during sealing operations. Another major negative is properly aligning the anvil and the sonotrode to obtain uniform pressure distribution. Another negative is the dust or excess material dispersed during the sealing operation. Yet another negative is the power necessary to generate the ultrasonic energy, and providing an anvil capable of withstanding the force of the ultrasonic energy. All of these negatives deter from the use of ultrasonic applicators on packaging machines that produce aseptic cartons.
Other methods of applying closures utilize hot melt to attach the flange of the closure to the material. Still others apply the closure to the carton after filling and sealing. One such post-processing application of closures to containers is described in European Patent Application 0838325 ("EPO '325"). EPO '325 discloses a fitment having a flange with a polyethylene band which has a current inductive wire confined within the band and having terminals protruding therefrom. During post-processing attachment, the closure is positioned on a container, and a current is fed through the wires to melt the polyethylene to bond the flange to a container. EPO '325 mentions that the wire could take the form of a strip or an electrically conductive layer within the band of the flange. EPO '325 only discloses integrating the "electrical heating element" into the flange such that a polyethylene/plastic layer covers the electrical heat element for heating thereby. It is obvious that EPO '325 utilizes the resistivity of the wire to generate heat when a current is applied to terminals on the closure. It is also necessary that the closure of EPO '325 have a "cutting" device to rupture the container since the closure is applied post-processing of the container.
Induction heat sealing has been used to seal a top-like closure to a cup-like container. One example is disclosed in U.S. Pat. No. 4,237,360 wherein a top and container are passed through a magnetic field to heat metal foils in the top and container in order to melt a resin for application of the top to the container. However, the induction heat sealing method of U.S. Patent 4,237,360 would not be applicable to sealing a closure with a flange, spout and cap to a container such as a gable top carton. Other problems have prevented the use of induction heat sealing of closures to containers. Thus, a need still exists for applying a closure to a container on a packaging machine prior to filling which does not involve ultrasonic sealing or hot melt.